Peripheral leukocytes from an Epstein-Barr associated aplastic anemia patient were used to establish an IL-2 dependent cell culture (JR). JR cells are CD4 positive and produce an HTLV-II like virus as determined by electron microscopy, reverse transcriptase analysis, PCR and Southern blot analysis. Both PCR and Southern blotting analysis of genomic DNA gave positive results using HTLV II specific probes but were negative with HTLV I and HIV probes. The JR virus is infectious determined by the presence of viral DNA in newly infected T and B cell lines. However, we have been unsuccessful in transforming cord blood cells with JR virus suggesting that the virus may be weakly or non transforming. Sera from patient JR was also positive for antibodies to HTLV I/II by ELISA and western blot, but was negative for HIV antibodies. This study suggests that HTLV II may play a role in aplastic anemia. Additional sera from aplastic anemia patients are being analyzed for antibodies to HTLV II. The JR cell lines represents only the fourth HTLV II infected cell line derived from a patient. Manuscript in preparation.